Mountains that rise from the seafloor, called seamounts, represent one of the most common ecosystems on earth, say scientists from the NOAA and Texas A&M University–Corpus Christi.

Their findings reverse previous beliefs about the prevalence of seamounts, which they say are "treasure troves" of marine biodiversity. The results are published in Oceanography.

Although researchers have thoroughly explored some 200 seamounts and mapped and sampled a hundred others, this study is the first to estimate that more than 45,000 seamounts dot the ocean floor worldwide — a total of roughly 28.8 million square kilometers or an area larger than the continent of South America.

The discovery was made possible using satellite altimetry data that measured incredibly slight changes in the sea surface height that, along with statistical analysis models, indicated the presence of these submerged mountains.

Locations of some of the world's major seamounts

(photo credit: wikipedia)

"Seamounts are biodiversity 'hotspots', with higher abundance and variety of life forms than the surrounding seafloor," said Tom Shirley, Ph.D., a conservation scientist with the Harte Research Institute at Texas A&M University-Corpus Christi. "In fact, new species are observed or collected on nearly every submersible dive." Two dozen new species of corals and sponges, for example, have been collected from seamounts in the Gulf of Alaska since 2002.

Seamounts not only make up the largest area of ocean habitat, they are also highly productive environments that can serve as habitats for important commercial fish species like orange roughy and sablefish, the researchers say.

"Unlike beaches or even coral reefs, most people will never see a seamount, but this study shows that they are clearly one of the predominant ecosystems on the planet," said Peter Etnoyer, Ph.D., amarine biologist at NOAA's Center for Coastal Environmental Health and Biomolecular Research. "We can only hope that through this study, people begin to realize what a vast unknown the ocean represents, and what a vital role it plays on Earth."

Citation: Peter J. Etnoyer, John Wood, and Thomas C. Shirley, 'How Large Is the Seamount Biome?', Oceanography, March 2010, 23(1)